The race reflected the divide in the state over Republican Gov. Scott Walker’s collective bargaining law, which would strip public workers of nearly all their union rights. The issue, which could ultimately be decided by the state Supreme Court, propelled the relatively unknown Kloppenburg into prominence and heightened voter interest in the election.

Kloppenburg, an assistant state attorney general, began her campaign with almost no name recognition and faced long odds against Prosser. The 12-year Supreme Court veteran emerged from a nonpartisan February primary with 55 percent of the vote, while Kloppenburg finished second out of four candidates with just 28 percent.

But opponents of the collective bargaining law opponents redefined the Supreme Court race as a referendum on Walker and all Republicans, working to leverage the anger over the measure against Prosser, a former GOP legislator. They branded him a Walker clone and held Prosser up as the best hope for stopping the measure.